data.gov.uk MCP — UK national open-data portal (CKAN API).
Four well-named, read-only tools with clear descriptions (avg 180 chars) and complete input schemas. All parameters are typed and described. Tool names follow verb_noun pattern (search_, list_, dataset_). Descriptions explain WHAT, WHEN, and WHAT IS RETURNED. However, output schemas are not documented, LLMs cannot predict response structure for downstream chaining. No error handling guidance. No pagination metadata (total count, next_cursor) documented for list tools. Parameter constraints (rows 1-1000, limit 1-1000) are stated in descriptions but not enforced via JSON Schema enums/min/max. Missing output schema documentation is the primary gap preventing a higher score.
Full dataset record by id or slug (CKAN package_show), including its resources. Each resource exposes a downloadable file: read "url" (the download link), "format" (CSV/XLSX/ZIP/etc.), and "name". data.gov.uk resources are files, not queryable datastore tables.
List publishing organizations on data.gov.uk (CKAN organization_list) — UK government departments, agencies, councils, NHS bodies, ONS, etc. Use a returned org "name" as fq="organization:<name>" in search_datasets to filter to that publisher.
Full details for one publishing organization (CKAN organization_show): display name, description, dataset count, and (optionally) a sample of its datasets. Use to learn what a given UK publisher releases.
Search the data.gov.uk catalogue (CKAN package_search) across 57k+ UK government open datasets. Returns matching datasets with titles, descriptions, publishing organization, and resources. Content is English. Pass an empty query to browse everything by relevance/sort.
Output schemas not documented. LLMs cannot predict response structure (fields, types, nested objects) for downstream tool chaining or data extraction. Breaks the pattern:tool-chain pattern.
Numeric parameter constraints (rows 1-1000, limit 1-1000, start ≥0) stated in descriptions but not enforced via JSON Schema min/max/enum. LLMs may pass invalid values; server-side validation is present but error messages are not documented.
Pagination support (rows, start, limit) documented but no guidance on total count, next_cursor, or result limits. LLMs cannot determine when to stop paginating or how many results to expect.
| Scored | Grade | Overall | Spec posture | Rubric |
|---|---|---|---|---|
| 2026-09-23 | C | 62 | 2026-07-28+ | v2 |
Error handling not documented. ckanGet() throws generic errors ('data.gov.uk: 404 ...') with no recovery guidance. LLMs cannot distinguish retryable (network) from user-fixable (invalid dataset ID) errors.
Parameter 'fq' (Solr filter query) requires domain knowledge of CKAN filter syntax. Description provides examples but no link to CKAN docs or validation rules. LLMs may construct invalid filters.